This invention relates generally to vehicle suspensions, and more particularly to an improved suspension for tandem-axle trucks.
The present invention is especially suited for beam-type suspensions where the axles of a tandem-axle truck are supported by beams pivoted to hangers on opposite sides of the frame of the truck. Springs (e.g., air bags) on the axle ends of the beams support the frame. Ideally, such suspensions are designed to be as lightweight as possible, to provide a soft ride and adequate roll stiffness or stability, that is, resistance to the tendency of the truck body to roll laterally during cornering, to provide an even distribution of the load over the wheels as the truck travels over bumps and as it turns, to provide good braking, to minimize torque applied to the axle as the vehicle encounters bumps in the road, and as it turns, and to eliminate so-called “dock walk”, which is the tendency of a vehicle to move away from a dock as it is being loaded. While certain prior designs have achieved some of these objectives, it has usually been at the sacrifice of other objectives. There is a need, therefore, for a suspension which represents an improvement over prior suspensions.